protocol HasInit {
    init()
    func sayHi()
}

extension HasInit {
    func sayHi() { print("Hi from an instance of \(type(of: self))") }
}

class A:HasInit {
    required init() { print("Init of \(type(of: self))") }
}

func makeInstance<T>(_ thetype:T.Type ) -> HasInit? {
    return (thetype as? HasInit.Type)?.init()
}


let aClassType = A.self
let aInstance = aClassType.init()
aInstance.sayHi()
let aaClass = type(of: aInstance)
makeInstance(aaClass)?.sayHi()


struct AS:HasInit {
     init() { print("Init of \(type(of: self))") }
}
let asStructType = AS.self
let asInstance = asStructType.init()
asInstance.sayHi()
makeInstance(type(of: asInstance))?.sayHi()